1. Field of the Invention
This invention relates to a corrosion detection method. More particularly, it is concerned with a corrosion detection agent which uses a water-soluble, electrochemically active compound to measure metal corrosion rates. The degree of reduction of the electrochemically active agent is correlated with the corrosion rate.
2. Description of the Prior Art
A major concern of chemical treatment in water systems is determination of the system metal corrosion rates. Without corrosion rate data, product overfeeding or underfeeding is common, which often is expensive or ineffective, and can lead to other problems.
Presently, corrosion can be detected either directly or indirectly. Direct detection is done by weight loss of the metal part itself (used in laboratory studies, but impractical in a plant situation), by visual inspection (expensive, time-consuming, and sometimes impossible), or by a variety of instrumental techniques (radiography, ultrasonics, eddy-current, thermography, acoustic emission) which are expensive and awkward or impossible in situ.
Indirect detection (metal coupons, corrosion meters) measures the corrosion potential of the water but does not tell whether active corrosion of plant equipment is occurring.
None of the presently used methods is able to give accurate corrosion rate measurements in a plant environment. Nevertheless, such techniques continue to be used because the resulting information is better than no information.
While the principle of using organic compounds to detect reducing sites in bacteria is widely used, no example has been found in the technical literature for using organic compounds for detecting reducing metal sites, e.g. corrosion.